The ability to deliver genes using cell surface receptors to achieve organ specific targeting in vivo has been demonstrated. This approach holds the promise of many exciting and effective therapies. The objective of this project is to develop chemically defined delivery systems that provide highly efficient delivery of genes into the nucleus of the targeted cells, first in vitro and then in vivo. Specific Aim 1 is to prepare, by organic synthesis, DNA binding polypeptides containing high affinity, chemically defined carbohydrate receptor ligands for the asialoglycoprotein receptor in the liver and for the mannose-6-phosphate receptor in skeletal muscle. Physical and chemical methods will be used to characterize the structural, thermodynamic, and kinetic properties of the DNA complexes. Specific Aim 2 is to determine, after endocytosis of the DNA:ligand complex and its release into the cytoplasm, what kind of structural and compositional changes in the complex are necessary for the DNA to move through the cytoplasm into the nucleus. DNA movement in the cytoplasm, DNA accumulation in the nucleus, and the probable dissociation of the complex in the cytoplasm will be measured using biochemical methods and digital imaging fluorescence microscopy. Specific Aim 3 is to synthesize DNA binding ligands that facilitate transport of the DNA through the cytoplasm into the nucleus. The SV-40 nuclear localization sequence on a DNA binding polypeptide will be tested as a component of the DNA complex. Specific Aim 4 is to demonstrate that the DNA complexes, constructed on the basis of in vitro experiments, are effective for gene delivery in vivo.